LawsIt is against the law for a Shinigami to give their spiritual power to Humans.

It is against the law for a Shinigami to use forbidden Kidō.

It is against the law for any citizen of Soul Society to create weapons of a dangerous nature not sanctioned by the feudal government. To do so is treason.

It is against the law to attack a captain. To do so is treason.

It is against the law to commit terrorist action or attempt overthrow of the balance of Soul Society. To do so is treason.

It is against the law to commit murder.

It is forbidden for a Shinigami to acquire Hollow powers.

It is by ancient law that two Shinigami cannot hold the same zanpakutō. They must fight for the honor of bearing the spirit, with the spirit going to the winner.

It is against the law for the Gotei 13 to meddle in the affairs of the noble families unless the family in question breaks one of the laws of Soul Society beyond a shadow of a doubt.

It is a crime for a Shinigami to remain in the human world longer than a certain time limit as this is viewed as living a second life.

Punishment

Exile: Certain crimes allows for the punishment of exile, commonly stripping a Shinigami of their powers and banishing them to the real world.

Detention: A not well known punishment among the citizens of Soul Society is the detention of high level shinigami. Commonly reserved for those who have either broken the law or quit the Gotei 13 or those who just seem dangerous and mentally unstable (as per the governments interpretation). This is carried out by the Special Forces.

There are several forms of executions in Soul Society, although only two have been revealed:

Spirit-sealing pit: The spirit-sealing pit is an ancient form of execution in which Shinigami criminals are thrown into a pit walled with deathstone – a type of stone that absorbs spiritual power, preventing those nearby from using their powers. Hollows are then thrown into the pit with the criminals as the means of execution. The practice was considered too barbaric and discontinued.

Sōkyoku (双): Sōkyoku is a form of execution usually reserved for those with extremely strong spiritual powers, namely shinigami captains. The Sōkyoku is a giant halberd that utterly destroys a soul on contact. When released, Sōkyoku takes on the form of a phoenix, its true form, called Kikōō. The Kikōō has the destructive power of one million zanpakutō, and that power is multiplied by a factor of 10 at the moment it pierces its victim.